Trim Pump

[zeezer]

I know it's early to be discussing this because the lakes are still frozen here in Michigan but here she goes anyways.
My trim pump gurgles when I lower the out drive into the water. I sounds fine when I lift it however. I unscrewed the plug on top, put a little more fluid into the tank & ran her up & down several times to bleed it, but the noise still persists. Any ideas?
What is the hydraulic fluid made of? Petrol, vegetable, synthetic?

Boat is a 1989 Wellcraft Nova 230 with Merc 260 & Alpha 1 series 1 Drive

 

[jtybt15]

I think you use 10wt motor oil. That is pretty much self bleeding. Just takes a few up/down cycles. Recheck fluid level the first few times as you expell air.

 

[zeezer]

Yup.........already tried with what I had left of some mercruiser trim oil. Problem is that it still gurgles. I trailer the boat, so I raise & lower the drive unit often.It still does it, so is it a bleeding issue or is there something on the pump that needs to be replaced?